In general, the structure designs of conventional cooling fins can be roughly classified into two categories, wherein one belongs to bar-type cooling fin applicable to medium and large machine (e.g. desktop computer) and the other one belongs to over-head cooling plate applicable to small machine (e.g. notebook computer). The bar-type cooling fin is illustrated in FIG. 1, the bar-type cooling fin 10 comprises a metal base board 11 having one side for contacting with an electronic component (e.g. CPU) and the other side thereof with a plurality of bar-type fins 12 arranged in a form of an array. As such, when the metal base board 11 receives heat conducted from the electronic component, the metal base board 11 will then conduct the heat to the bar-type fins 12 so that the total heat energy of the metal base board 11 can be distributed to the bar-type fins 12 and further dissipated to the air so as to reduce the heat of the electronic component.
In addition, please refer to the over-head cooling plate as shown in FIG. 2. The over-head cooling plate 13 is composed of a metal plate 14. Both free ends of the metal plate 14 rise up a height and then oppositely extend therefrom a length horizontally to form a contact surface 15 respectively such that the over-head cooling plate 13 is formed as a “T” shape. The two contact surfaces 15 are coupled with the inner side of the case of the small machine. Therefore, when the metal plate 14 receives heat conducted from the electronic component, the metal plate 14 can conduct the heat thereof to the case via the two contact surfaces 15 to reduce the heat of the electronic component.
Whereas, when a regular electronic component is operating, it will generate electromagnetic noise and radiate it to the ambient environment. Such noise can be further transmitted to a circuit board and another electronic component (e.g. graphics chip) or transmitted along the radial paths inside the case. In general, since the regular cooling plate is made of metal material, the heat of the cooling plate and the electronic component can be mutually coupled when the cooling plate contacts with the electronic component, allowing the electromagnetic noise of the electronic component to be transmitted to the cooling plate. Besides, the cooling plate can also be treated as an antenna to absorb the noise transmitted along radial directions inside the case.
Since the cooling plate can also be used as an antenna, the noise absorbed by the cooling plate can be radiated to the ambient environment. Furthermore, by means of the energy coupling between electronic components, the noise will eventually be transmitted back to the electronic component. Therefore, how to design a structure of cooling plate capable of eliminating the electromagnetic noise is a crucial subject needed to be resolved currently.